
Postcard from the Summit – CFHT Sunset

Pāhoehoe
Mele Kalikimaka
The Moon and Jupiter
Tonight will find the Moon about 7° away from Jupiter. Tomorrow the pair will be even closer, a separation of only 4.5°. The pair will be well up at sunset, to dominate the sky for much of the night.
Mercury Exits the Dawn
This week Mercury will be exiting the dawn sky, sliding closer to the Sun in our sky each day. It will pass through superior conjunction on January 17th, heading for an evening apparition beginning in the final days of January.
Trek to the Lava
The lava has been entering the sea for over a month now. I have wanted to hike out, but life and other commitments have consistently intervened. With off-island guests, I made the offer to lead a hike out to the flowing lava. My sister-in-law Darcy was the only one that took me up on the offer, the prospect of a 2am wake-up and a two hour trek across rough ground too much for some. We left the others in bed.

Postcard from the Summit – Hard Headed
Winter Solstice
Winter solstice occurs today at 01:12HST. Today the Sun will occupy the most southerly position in the sky of the year. The term solstice comes from the latin terms Sol (the Sun) and sistere (to stand still). On this day the Sun seems to stand still as it stops moving southwards each day and begins move to the north. This is the first day of winter as marked by many cultures in the northern hemisphere.
| 2012 Solstices and Equinoxes | ||||
|---|---|---|---|---|
| UT | HST | |||
| Perihelion | Jan 5 | 03:59UT | Jan 4 | 17:59HST |
| Spring Equinox | Mar 20 | 05:14UT | Mar 19 | 19:14HST |
| Summer Solstice | Jun 20 | 23:09UT | Jun 20 | 13:09HST |
| Apehelion | Jul 4 | 23:59UT | Jul 4 | 13:59HST |
| Fall Equinox | Sep 22 | 14:49UT | Sep 22 | 04:49HST |
| Winter Solstice | Dec 21 | 11:12UT | Dec 21 | 01:12HST |
| Source: USNO Data Services Website and the NASA Sky Calendar | ||||
Working the Weather
One of the little side jobs I have gotten assigned at Keck is updating the weather station. This involves replacing all of the weather monitoring equipment that allows the operators to keep an eye on conditions around the telescopes. This gear is absolutely critical, giving the operators the data they need to protect our equipment, including the irreplaceable mirrors.

It has been fun to learn about measuring temperature, humidity, dew point and more. It seems so simple at first, but the complications of getting a good reading are subtle. Passive instrument shelters, active ventilation, instrument positioning, calibration and more. Issues that can make a good instrument give bad data.

Last week I installed a new barometric sensor. This was the last part of the existing weather instrument suite that needed to be replaced. I got lucky, it was a great day on the summit, sunny with just a modest breeze. Just the day to spend a couple hours hanging off the weather mast in a climbing harness rewiring a junction box for the new cables. A few holes to drill, a few bolts, a couple cables… done!
My next item is to install an anemometer. We have not had an operational anemometer in many years and our observing staff has made it abundantly clear that they want an anemometer. Not that this one will be easy, it is a bit of a challenge to get a decent wind reading anywhere near a 100ft diameter dome. This challenge will be a bit more involved, and involve some good engineering fun. Time to learn about measuring wind-speed and how to do it right. Looking forward to the next part of the plan!


